Gila monster

One is on exhibit at the Reptile House housed with the western diamondback rattlesnake – these species also share habitat in the wild.

The remaining five Gila monsters are part of a husbandry research project and housed off-exhibit.

Where to find me in the Zoo

The Reptile House

Fun Facts

A synthetic version of a protein found in Gila monster saliva is used as a treatment for diabetes in humans.

Though a Gila monster bite is extremely painful, none has resulted in a reported human death.

They can store fat in their oversized tails and are able to go months between meals.

Ask an Expert

Have a question about this animal?Ask an expert on our Docent Council!

There are two subspecies of gila monsters. The reticulated gila monster features more evenly distributed light and dark markings. The banded gila monster's light patterns dominate its appearance. In both subspecies, their patterns will change over time and become more distinctive. The gila monster is poisonous, although its bite is not fatal to humans.

The body of the gila monster is heavy and stocky with a large head, widespread legs and a stumpy tail. It is one of the largest lizards found in the United States.

The gila monster is different than most other lizards in appearance. Its scales are small and rounded and don't overlap like most other reptiles. gila monsters are also very vibrant in color and pattern. Its body is a blend of black, yellow, pink or orange spots.

They're usually found among rocky areas with shrubs and gravel. During hot weather, the gila monster uses its forelimbs to burrow underground and shelter itself from the hot desert sun.

Longevity

17 years in captivity.

Reproduction

Gila monsters mate during the late spring months. It's common for males to challenge other males for mating rights by biting each other. Fortunately, gila monsters are immune to their own venom so a bite is not fatal.

A female will produce up to 12 eggs, but they may take up to 10 months to hatch. An adult gila monster reaches its maturity at two years.

Behavior

The gila monster moves rather sluggishly through the desert, however it's quick to catch its prey by snapping its jaw. It's most active at night and will often stay burrowed underground when the temperatures are extreme. Since they don't eat often, they're able to remain relatively inactive except when searching for breeding dens or basking sites to capture the warmth of the sun.

Size

An adult can reach up to 21 inches in length.

Weight

An adult can weight up to five pounds.

Diet

In the wild, the gila monster feeds on small rodents and mammals, which it digs out of the ground using its powerful forelimbs. It also eats bird and reptile eggs. Like a snake, the gila monster uses its fork-like tongue to pick up the scent of its prey. During the warmer months, the gila monster consumes the bulk of its diet at night. It uses its short tail for fat storage during the winter months. In the wild they may only eat 5-10 times a year. Here at the Zoo, the gila monsters eat mice or rats they're fed every few weeks.

Geographic Range

Gila monsters live in the deserts of the southwestern United States and Mexico.

Conservation Status

On the 2011 IUCN Red List of Threatened Species, the gila monster is listed as Near Threatened.

To learn more about the conservation efforts at the Philadelphia Zoo, click here.